Quote - I have had migraine headaches on and off for a long time, and I blamed too much time on my PC and bad eyes. Two weeks ago I replaced my 22" CRT Trinatron monitor that was burning out with a nice clear and bright 24" LCD. All of a sudden my headaches are gone and my eyes no longer burn. I can't believe a slightly larger monitor could help that much, but is seems to have gotten rid of my headaches. Has anyone else had a similar experience?

There are many people who have this problem with CRT displays. The problem isn't so much a "low" refresh rate, as it is a "beat frequency" with surrounding lighting.

If you live in the United States where the power line frequency is 60 Hz, and Windows sets your default monitor refresh frequency to 60 Hz (very common), the lights in your room will cause your monitor to appear to flicker due to slight phase and frequency variations between independant monitor 60Hz frequency source vs. the 60 Hz line frequency. The effect is more pronounced under florescent lights (which have a very frequency-dependant light output) than an incandescant bulb (which is more "filtered" due to slow response of the heated wire).

The effects are more noticable in high-contrast regions: black text on a white background, for example.

Also, since your eyes are highly customized to detect unusual motion from your peripheral vision (a survival trait - think of lions attacking you from the side), you can easily spot a 60 Hz CRT monitor by turning you head slightly away from the monitor and catching the flicker through your peripheral vision.

I can almost instantly spot when somebody has their monitor set at 60 Hz. I have never been wrong in detecting one yet, either.

LCD have a much slower frequency response than a CRT, so the flickering effect is minimized on an LCD monitor set to 60 Hz than a CRT at 60 Hz